This invention relates to a device and method for shipping and dispensing precise amounts of dry particulate matter, such as fertilizer and pesticide products and such, into a liquid carrier stream.
Many useful agricultural chemicals and other such products are distributed in dry bulk form, either as powders, granules or small pellets, but are ultimately dissolved into a liquid carrier for application by spraying or irrigation equipment. Thus, a farmer will either purchase the chemicals dry, either in bags or bins, and mix them with water or other liquid carrier as needed, such as by pouring the dry chemicals and liquid carrier separately into a mixing tank, or will transport a tank to a chemical dealer who will dispense a pre-mixed solution into the tank. Unfortunately, environmental and safety regulations are typically more stringent regarding the transportation of chemicals in liquid form than in dry form.
Pneumatic systems have been developed for metering and transporting dry particulate matter in a stream of air, from a bulk storage bin to a mixing tank for subsequent mixing with a liquid. A useful example of such a system is a portable unit described in U.S. Pat. No. 5,803,673 and sold under the trade name xe2x80x9cACCUBINxe2x80x9d. The entire contents of the above-referenced patent are incorporated herein by reference as if fully set forth.
With many agricultural chemicals, prolonged exposure to high concentrations of air-borne particulates is not desirable.
The invention features a means of transporting and storing a dry particulate material, and then dispensing controlled quantities of that material directly into a stream of liquid carrier. The invention is particularly applicable for use with agricultural chemicals, such as pesticides (e.g., herbicides), fertilizers and adjuvants. By xe2x80x9cparticulate formxe2x80x9d, we mean to include powders, granular and pelletized materials that are not suspended in a liquid medium.
According to one aspect of the invention, a device is provided for dispensing precise amounts of dry particulate matter directly into a liquid carrier stream. The device includes a bin for holding a quantity of particulate matter, a conduit for transporting a stream of liquid carrier, and a meter connected to the bin for controllably releasing a desired amount of the particulate matter from the bin into the conduit while disallowing entry of the liquid carrier to the bin. The bin, conduit and meter are all mounted upon a portable structure for transportation with particulate matter in the bin.
In the embodiment discussed in more detail below, the meter is arranged at the bottom end of the bin, such that the particulate matter is fed into the meter by gravitational force.
In some embodiments, the meter includes a multi-vaned rotor constrained to rotate within a housing, with the rotor vanes defining between them discrete pockets of known volume. These pockets preferably each have a volume of less than about 30 cubic inches (500 cubic centimeters), more preferably less than about 25 cubic inches (400 cubic centimeters), and most preferably less than about 10 cubic inches (150 cubic centimeters).
In some cases, the meter also includes an electric drive motor for driving the rotor.
In presently preferred embodiments, the device includes a controller for controlling the number of revolutions of the motor, and, thereby, the volume of particulate matter released from the bin.
For supplying electrical power to the motor, an electrical storage battery may be mounted to the portable structure. In some instances, a battery charger may be adapted to receive power from an external source to recharge the battery. The battery may also be adapted to supply electrical power to the controller.
In some embodiments, an electronic programmable controller is included. The controller is adapted to operate the meter to release a desired volume of particulate matter, in accordance with operator input. This controller is preferably mounted upon the portable structure, but in other embodiments the controller may be a separable unit, with an electrical port provided on the inductor for attaching the remote electronic controller for controllably operating the meter.
In some instances, the controller is adapted to receive an operator input representing a desired weight of matter to be released and to calculate, based upon at least this input and a stored particulate matter density value, a corresponding volume of matter to be released.
When a preset amount of matter has been released, in some cases the controller is adapted to automatically stop releasing the particulate matter, while liquid carrier continues to flow along the conduit. Under such conditions, the controller is preferably adapted to alert an operator when the preset amount of particulate matter has been released.
In some embodiments, the conduit is adapted to apply a sub-atmospheric pressure to the released particulate matter, in the presence of an operative liquid carrier flow, to motivate the released matter into the conduit. This conduit may include an eductor, for example, which effectively forms a venturi. Such an eductor is preferably constructed to dissolve the particulate matter into the carrier liquid within the eductor, or as soon as possible thereafter. Preferably, the conduit is adapted to apply a vacuum of between about 0.5 and 6 pounds per square inch (3.4 and 41 kilo-pascals) below atmospheric pressure to the released particulate matter.
In some embodiments a check valve is disposed between the conduit and the meter. The check valve is adapted to be normally closed and to open when the sub-atmospheric pressure falls below a predetermined threshold, thereby applying the sub-atmospheric pressure to the downstream side of the meter. In some cases, a pressure switch responsive to this sub-atmospheric pressure is included, for enabling operation of the meter only in the presence of a desired amount of vacuum. In such cases, the pressure switch is located between the check valve and the meter.
Preferably, the bin comprises a hopper with sides sloped at an angle of between about 45 and 60 degrees from horizontal. It is also preferred that the hopper have an internal volume of between about 5 and 200 cubic feet (0.14 and 5.7 cubic meters).
In some cases, a vibrator is structurally connected to the bin and adapted to vibrate the bin during operation to assist flow of the particulate matter into the meter.
Preferably the portable structure has a base footprint sufficiently small to fit within a 4 foot by 8 foot (1.2 meter by 2.4 meter) rectangle. For example, one preferred embodiment has a base footprint of about 42 inches by 48 inches (1.0 meter by 1.2 meters).
According to another aspect of the invention, a method of dispensing precise amounts of dry particulate matter directly into a liquid carrier stream is provided. The method includes first connecting the conduit of the device of the invention, the bin of which contains particulate matter, to a source of liquid carrier; and then motivating a flow of the liquid carrier through the conduit, thereby dispensing a desired amount of the particulate matter from the bin of the device into the flow of liquid carrier.
In some cases, the particulate matter comprises an agricultural pesticide, fertilizer or adjuvant.
The liquid carrier may comprise water or a liquid fertilizer, for instance.
In some instances, the flow of liquid carrier is directed from the conduit of the device to a receptacle.
Where the device includes an electronic controller for controlling the meter of the device, the method may further include, prior to the step of motivating, entering a value into the controller representing a desired amount of particulate matter to be released. The method may also include, prior to the step of motivating, entering a value into the controller representing the density of the particulate matter to be released.
According to another aspect of the invention, a method of distributing agricultural chemicals in particulate form, to be mixed with a liquid carrier before use, is provided. The method includes the steps of:
(1) providing multiple devices constructed according to the invention, as described above;
(2) distributing the devices, with corresponding quantities of agricultural chemicals, to individual end users for dispensing the agricultural chemicals into liquid carrier streams at remote locations; and then
(3) accepting the devices as returned from the end users, after the end users have dispensed at least some of the distributed chemicals.
In some embodiments, the method also includes, before distributing each device, filling the bin of the device with the corresponding quantity of agricultural chemical; and then, after accepting the returned devices, refilling the bins of the devices with additional agricultural chemicals.
By using an inductor constructed according to the invention, a dry chemical substance can be properly and accurately metered directly into a liquid carrier, without possibly harmful exposure to chemical dust and fumes. Additionally, transportation of pre-mixed liquid chemicals can be avoided, with the chemicals being transported all the way to their use site in dry form. Simple, automated operation at remote sites may be provided by a control system that is adapted to run on on-board batteries, with very little operator input. Other advantages and features will also be understood from the following description of embodiments.